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target: split target_submit_cmd_map_sgls 
Separate target_submit_cmd_map_sgls into the part that does:
- the initial cmd setup
- will not sleep
- and gives us access to the se_device
and the part that:
- can sleep
- handles the actual submission

This will be needed for loop in the next patches which needs to add
the cmd to the lio workqueue and can't sleep in that initial submission
path.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
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@mikechristie @intel-lab-lkp
mikechristie authored and intel-lab-lkp committed Feb 9, 2021
1 parent d48f4e4 commit 3382952197b63f11c166ff293f819ce6ac4d52ae
Showing 1 changed file with 109 additions and 40 deletions.
149 drivers/target/target_core_transport.c
View file
@@ -1566,12 +1566,9 @@ transport_generic_map_mem_to_cmd(struct se_cmd *cmd, struct scatterlist *sgl,
}

/**
* target_submit_cmd_map_sgls - lookup unpacked lun and submit uninitialized
* se_cmd + use pre-allocated SGL memory.
*
* target_submit_prep - prep cmd for submission to lio core
* @se_cmd: command descriptor to submit
* @se_sess: associated se_sess for endpoint
* @cdb: pointer to SCSI CDB
* @sense: pointer to SCSI sense buffer
* @unpacked_lun: unpacked LUN to reference for struct se_lun
* @data_length: fabric expected data transfer length
@@ -1587,26 +1584,29 @@ transport_generic_map_mem_to_cmd(struct se_cmd *cmd, struct scatterlist *sgl,
*
* Task tags are supported if the caller has set @se_cmd->tag.
*
* Returns non zero to signal active I/O shutdown failure. All other
* setup exceptions will be returned as a SCSI CHECK_CONDITION response,
* but still return zero here.
* Returns:
* - less than zero to signal active I/O shutdown failure
* - zero on success.
* - one for all other setup exceptions. The cmd will be returned as a
* SCSI CHECK_CONDITION response in this case.
*
* This may only be called from process context, and also currently
* assumes internal allocation of fabric payload buffer by target-core.
* This may only be called from interrupt context if the caller's
* queue_status and release_cmd callouts do not block.
*
* This assumes internal allocation of fabric payload buffer by target-core.
*/
int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess,
unsigned char *cdb, unsigned char *sense, u64 unpacked_lun,
u32 data_length, int task_attr, int data_dir, int flags,
struct scatterlist *sgl, u32 sgl_count,
struct scatterlist *sgl_bidi, u32 sgl_bidi_count,
struct scatterlist *sgl_prot, u32 sgl_prot_count)
static int
target_submit_prep(struct se_cmd *se_cmd, struct se_session *se_sess,
unsigned char *sense, u64 unpacked_lun,
u32 data_length, int task_attr, int data_dir, int flags,
struct scatterlist *sgl, u32 sgl_count,
struct scatterlist *sgl_bidi, u32 sgl_bidi_count,
struct scatterlist *sgl_prot, u32 sgl_prot_count)
{
struct se_portal_group *se_tpg;
sense_reason_t rc;
int ret;

might_sleep();

se_tpg = se_sess->se_tpg;
BUG_ON(!se_tpg);
BUG_ON(se_cmd->se_tfo || se_cmd->se_sess);
@@ -1637,28 +1637,14 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess
*/
if (flags & TARGET_SCF_BIDI_OP)
se_cmd->se_cmd_flags |= SCF_BIDI;

rc = target_cmd_init_cdb(se_cmd, cdb);
if (rc) {
transport_send_check_condition_and_sense(se_cmd, rc, 0);
target_put_sess_cmd(se_cmd);
return 0;
}

/*
* Locate se_lun pointer and attach it to struct se_cmd
*/
rc = transport_lookup_cmd_lun(se_cmd);
if (rc) {
transport_send_check_condition_and_sense(se_cmd, rc, 0);
target_put_sess_cmd(se_cmd);
return 0;
}

rc = target_cmd_parse_cdb(se_cmd);
if (rc != 0) {
transport_generic_request_failure(se_cmd, rc);
return 0;
return 1;
}

/*
@@ -1679,6 +1665,43 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess
if (sgl_count != 0) {
BUG_ON(!sgl);

rc = transport_generic_map_mem_to_cmd(se_cmd, sgl, sgl_count,
sgl_bidi, sgl_bidi_count);
if (rc != 0) {
transport_generic_request_failure(se_cmd, rc);
return 1;
}
}

return 0;
}

/**
* target_submit - perform final initialization and submit cmd to LIO core
* @se_cmd: command descriptor to submit
* @cdb: pointer to SCSI CDB
*
* target_submit_prep must have been called on the cmd, and this must be
* called from process context.
*/
static void target_submit(struct se_cmd *se_cmd, unsigned char *cdb)
{
struct scatterlist *sgl = se_cmd->t_data_sg;
unsigned char *buf = NULL;
int rc;

might_sleep();

rc = target_cmd_init_cdb(se_cmd, cdb);
if (rc)
goto fail;

rc = target_cmd_parse_cdb(se_cmd);
if (rc != 0)
goto fail;

if (se_cmd->t_data_nents != 0) {
BUG_ON(!sgl);
/*
* A work-around for tcm_loop as some userspace code via
* scsi-generic do not memset their associated read buffers,
@@ -1689,8 +1712,6 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess
*/
if (!(se_cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) &&
se_cmd->data_direction == DMA_FROM_DEVICE) {
unsigned char *buf = NULL;

if (sgl)
buf = kmap(sg_page(sgl)) + sgl->offset;

@@ -1700,12 +1721,6 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess
}
}

rc = transport_generic_map_mem_to_cmd(se_cmd, sgl, sgl_count,
sgl_bidi, sgl_bidi_count);
if (rc != 0) {
transport_generic_request_failure(se_cmd, rc);
return 0;
}
}

/*
@@ -1715,6 +1730,60 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess
core_alua_check_nonop_delay(se_cmd);

transport_handle_cdb_direct(se_cmd);
return;

fail:
transport_generic_request_failure(se_cmd, rc);
}

/**
* target_submit_cmd_map_sgls - lookup unpacked lun and submit uninitialized
* se_cmd + use pre-allocated SGL memory.
*
* @se_cmd: command descriptor to submit
* @se_sess: associated se_sess for endpoint
* @cdb: pointer to SCSI CDB
* @sense: pointer to SCSI sense buffer
* @unpacked_lun: unpacked LUN to reference for struct se_lun
* @data_length: fabric expected data transfer length
* @task_attr: SAM task attribute
* @data_dir: DMA data direction
* @flags: flags for command submission from target_sc_flags_tables
* @sgl: struct scatterlist memory for unidirectional mapping
* @sgl_count: scatterlist count for unidirectional mapping
* @sgl_bidi: struct scatterlist memory for bidirectional READ mapping
* @sgl_bidi_count: scatterlist count for bidirectional READ mapping
* @sgl_prot: struct scatterlist memory protection information
* @sgl_prot_count: scatterlist count for protection information
*
* Task tags are supported if the caller has set @se_cmd->tag.
*
* Returns non zero to signal active I/O shutdown failure. All other
* setup exceptions will be returned as a SCSI CHECK_CONDITION response,
* but still return zero here.
*
* This may only be called from process context, and also currently
* assumes internal allocation of fabric payload buffer by target-core.
*/
int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess,
unsigned char *cdb, unsigned char *sense, u64 unpacked_lun,
u32 data_length, int task_attr, int data_dir, int flags,
struct scatterlist *sgl, u32 sgl_count,
struct scatterlist *sgl_bidi, u32 sgl_bidi_count,
struct scatterlist *sgl_prot, u32 sgl_prot_count)
{
int ret;

ret = target_submit_prep(se_cmd, se_sess, sense, unpacked_lun,
data_length, task_attr, data_dir, flags,
sgl, sgl_count, sgl_bidi, sgl_bidi_count,
sgl_prot, sgl_prot_count);
if (ret < 0)
return ret;
else if (ret > 0)
return 0;

target_submit(se_cmd, cdb);
return 0;
}
EXPORT_SYMBOL(target_submit_cmd_map_sgls);

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